Abstract

Improved methods for assessing cereal crop feed value are a prerequisite for the genetic improvement of sorghum [Sorghum bicolor (L.) Moench] feed value. Rate of starch digestion is now commonly believed to be the limiting factor in sorghum utilization by cattle (Bos taurus). However, techniques to assess this trait are not useful to sorghum breeders because of high labor inputs, lab error associated with starch measurement, and need for high numbers of replications. The objective of this study was to develop a simple technique capable of identifying differences in digestion between sorghum and corn (Zea mays L.) and detecting differences among sorghum genotypes. In vitro starch and dry matter digestion were measured on sorghum and corn lab standards at 0, 6, 12, 18, 24, 30, and 40 h. Maximum differentiation between corn and sorghum dry matter digestion (345 vs. 253 g kg−1) and starch digestion (403 vs. 301 g kg−1) occurred at 12 h, and dry matter and starch digestion were highly correlated (r = 0.99). Differences among five sorghum lines were significant for 12-h dry matter digestion and ranged from 229 to 272 g kg−1 This procedure provides a precise and rapid technique that can be used by feed grain breeders to evaluate modifications in grain digestion parameters.

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